﻿<p>A covering is an element which covers some part of another element and is fully dependent on that other element. The
<em>IfcCovering</em> defines the occurrence of a covering type, that (if given) is expressed by the <em>IfcCoveringType</em>.</p>

<blockquote class="extDef">NOTE&nbsp; Definition according to ISO ISO 6707-1: final coverings and treatments of surfaces and their
intersections.</blockquote>

<p>Coverings are elements with relationships to the covered element and the space on the other side, they may contain openings,
assigned by <em>IfcRelVoidsElement</em>, material information, assigned by <em>IfcRelAssociatesMaterial</em>, and others.</p>

<blockquote class="example">
EXAMPLE&nbsp; Coverings include wall claddings, floorings, suspended ceilings, moldings and skirting boards.
</blockquote>

<blockquote class="note">
NOTE&nbsp; A more basic information about claddings, floorings, and ceilings of a space can be attached to <em>IfcSpace</em>'s using the 
Pset_SpaceCommon properties. Then only a name can be provided and the covering quantities would be interpreted from the space quantities.
</blockquote>

<p>Coverings can be assigned to</p>
<ul>
<li>a space represented by <em>IfcSpace</em>
<ul>
<li>using the inverse relationship <em>CoversSpaces</em> pointing to <em>IfcRelCoversSpaces</em>. The space is then accessible via
<em>IfcRelCoversSpaces.RelatedSpace</em>. It defines to which space a covering is facing towards.</li>
</ul>
</li>
<li>a space boundary represented by <em>IfcRelSpaceBoundary</em>
<ul>
<li>using the inverse relationship <em>ProvidesBoundaries</em> pointing to <em>IfcRelSpaceBoundary.</em> The space is then
accessible via <em>IfcRelSpaceBoundary.RelatingSpace</em>.</li>
</ul>
</li>
<li>a building element represented by <em>IfcBuildingElement</em>
<ul>
<li>using the inverse relationship <em>Covers</em> pointing to <em>IfcRelCoversBldgElements</em>. The building element is then
accessible via
<em>IfcRelCoversBldgElements.RelatingBuildingElement</em>.</li>
</ul>
</li>
</ul>

<blockquote class="note">NOTE&nbsp; The mere containment relationship between an <em>IfcCovering</em> and an <em>IfcSpace</em> is created
by using <em>IfcRelContainedInSpatialStructure</em></blockquote>
<p>The following guideline shall apply:</p>
<ul>
<li>(default) if the space has coverings that may not have their own shape representation and no defined relationships to the building
elements they cover, then the <em>IfcCovering</em> shall be assigned to <em>IfcSpace</em> using the <em>IfcRelCoversSpaces</em>
relationship,</li>
<li>if the space has coverings that have an own shape representation and the space has defined space boundaries, then the
covering, which relates to that space, shall be contained in the space using <em>IfcRelContainedInSpatialStructure</em>. It may be
assigned to the space boundaries using the <em>IfcRelSpaceBoundary</em>.</li>
<li>if the covering does not relate to a space, then the covering should be assigned to the building element or a distribution
element using the <em>IfcRelCoversBldgElements</em> relationship.</li>
</ul>
<blockquote class="history">
HISTORY&nbsp; New entity in IFC1.0.
</blockquote>
<blockquote class="change-ifc2x">
IFC2x CHANGE&nbsp; The attribute <em>PredefinedType</em> is now optional and should only be inserted when no type information, given by <em>IfcCoveringType</em>, is assigned to the <em>IfcCovering</em> occurrence by <em>IfcRelDefinesByType</em>.
</blockquote>